Components with hierarchy

You can define components Parametric cells (waveguides, bends, couplers) with basic input parameters (width, length, radius …) and reuse the PCells in more complex PCells.

from functools import partial
import toolz

from gdsfactory.typings import ComponentSpec

import gdsfactory as gf
from gdsfactory.generic_tech import get_generic_pdk

gf.config.rich_output()
PDK = get_generic_pdk()
PDK.activate()

2023-02-20 17:48:53.474 | INFO     | gdsfactory.config:<module>:50 - Load '/home/runner/work/gdsfactory/gdsfactory/gdsfactory' 6.43.1
2023-02-20 17:48:54.378 | INFO     | gdsfactory.technology.layer_views:__init__:785 - Importing LayerViews from YAML file: /home/runner/work/gdsfactory/gdsfactory/gdsfactory/generic_tech/layer_views.yaml.
2023-02-20 17:48:54.385 | INFO     | gdsfactory.pdk:activate:206 - 'generic' PDK is now active

@gf.cell
def bend_with_straight(
    bend: ComponentSpec = gf.components.bend_euler,
    straight: ComponentSpec = gf.components.straight,
) -> gf.Component:
    c = gf.Component()
    b = gf.get_component(bend)
    s = gf.get_component(straight)

    bref = c << b
    sref = c << s

    sref.connect("o2", bref.ports["o2"])
    c.info["length"] = b.info["length"] + s.info["length"]
    return c


c = bend_with_straight()
print(c.metadata['info']['length'])
c

26.637

bend_with_straight: uid c53b8465, ports [], references ['bend_euler_1', 'straight_1'], 0 polygons

ComponentSpec

When defining a Parametric cell you can use other ComponentSpec as an argument. It can be a:

1. string: function name of a cell registered on the active PDK. "bend_circular"

2. dict: dict(component='bend_circular', settings=dict(radius=20))

3. function: Using functools.partial you can customize the default parameters of a function.

1. string

c = bend_with_straight(bend="bend_circular")
c

bend_with_straight_bend_840d811a: uid b1db8557, ports [], references ['bend_circular_1', 'straight_1'], 0 polygons

2. dict

Lets customize the functions that we pass. For example, we want to increase the radius of the bend from the default 10um to 20um.

c = bend_with_straight(bend=dict(component="bend_circular", settings=dict(radius=20)))
c

bend_with_straight_113977eb: uid 89dc019c, ports [], references ['bend_circular_1', 'straight_1'], 0 polygons

3. function

Partial lets you define different default parameters for a function, so you can modify the settings for the child cells.

c = bend_with_straight(bend=gf.partial(gf.components.bend_circular, radius=30))
c

bend_with_straight_e172a9e6: uid b55cf7c6, ports [], references ['bend_circular_1', 'straight_1'], 0 polygons

bend20 = partial(gf.components.bend_circular, radius=20)
b = bend20()
b

bend_circular_radius20: uid f28bc79d, ports ['o1', 'o2'], references [], 1 polygons

type(bend20)

<class 'functools.partial'>

bend20.func.__name__

'bend_circular'

bend20.keywords

{'radius': 20}

b = bend_with_straight(bend=bend20)
print(b.metadata['info']['length'])
b

41.416

bend_with_straight_e917218d: uid 4319af97, ports [], references ['bend_circular_1', 'straight_1'], 0 polygons

# You can still modify the bend to have any bend radius
b3 = bend20(radius=10)
b3

bend_circular_radius10: uid c25a94aa, ports ['o1', 'o2'], references [], 1 polygons

PDK custom fab

You can define a new PDK by creating function that customize partial parameters of the generic functions.

Lets say that this PDK uses layer (41, 0) for the pads (instead of the layer used in the generic pad function).

You can also access functools.partial from gf.partial

pad = gf.partial(gf.components.pad, layer=(41, 0))

c = pad()
c

pad_layer41__0: uid 115f5d81, ports ['e1', 'e2', 'e3', 'e4', 'pad'], references ['compass_1'], 0 polygons

Composing functions

You can combine more complex functions out of smaller functions.

Lets say that we want to add tapers and grating couplers to a wide waveguide.

c1 = gf.components.straight()
c1

straight: uid 35b0a132, ports ['o1', 'o2'], references [], 1 polygons

straight_wide = gf.partial(gf.components.straight, width=3)
c3 = straight_wide()
c3

straight_width3: uid 21b1940e, ports ['o1', 'o2'], references [], 1 polygons

c1 = gf.components.straight(width=3)
c1

straight_width3: uid 21b1940e, ports ['o1', 'o2'], references [], 1 polygons

c2 = gf.add_tapers(c1)
c2

straight_width3_add_tap_9ae57f22: uid 5b1d4496, ports ['o1', 'o2'], references ['taper_1', 'taper_2', 'straight_1'], 0 polygons

c2.metadata_child['changed']  # You can still access the child metadata

{'width': 3}

c3 = gf.routing.add_fiber_array(c2, with_loopback=False)
c3

straight_width3_add_tap_c79a46d8: uid def6f0de, ports ['opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o1', 'opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o2'], references ['bend_euler_1', 'straight_1', 'straight_2', 'bend_euler_2', 'straight_3', 'straight_4', 'grating_coupler_elliptical_trenches_1', 'grating_coupler_elliptical_trenches_2', 'add_tapers_1'], 0 polygons

c3.metadata_child['changed']  # You can still access the child metadata

{'width': 3}

Lets do it with a single step thanks to toolz.pipe

add_fiber_array = gf.partial(gf.routing.add_fiber_array, with_loopback=False)
add_tapers = gf.add_tapers

# pipe is more readable than the equivalent add_fiber_array(add_tapers(c1))
c3 = toolz.pipe(c1, add_tapers, add_fiber_array)
c3

straight_width3_add_tap_c79a46d8: uid def6f0de, ports ['opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o1', 'opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o2'], references ['bend_euler_1', 'straight_1', 'straight_2', 'bend_euler_2', 'straight_3', 'straight_4', 'grating_coupler_elliptical_trenches_1', 'grating_coupler_elliptical_trenches_2', 'add_tapers_1'], 0 polygons

we can even combine add_tapers and add_fiber_array thanks to toolz.compose or toolz.compose

For example:

add_tapers_fiber_array = toolz.compose_left(add_tapers, add_fiber_array)
c4 = add_tapers_fiber_array(c1)
c4

straight_width3_add_tap_c79a46d8: uid def6f0de, ports ['opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o1', 'opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o2'], references ['bend_euler_1', 'straight_1', 'straight_2', 'bend_euler_2', 'straight_3', 'straight_4', 'grating_coupler_elliptical_trenches_1', 'grating_coupler_elliptical_trenches_2', 'add_tapers_1'], 0 polygons

is equivalent to

c5 = add_fiber_array(add_tapers(c1))
c5

straight_width3_add_tap_c79a46d8: uid def6f0de, ports ['opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o1', 'opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o2'], references ['bend_euler_1', 'straight_1', 'straight_2', 'bend_euler_2', 'straight_3', 'straight_4', 'grating_coupler_elliptical_trenches_1', 'grating_coupler_elliptical_trenches_2', 'add_tapers_1'], 0 polygons

as well as equivalent to

add_tapers_fiber_array = toolz.compose(add_fiber_array, add_tapers)
c6 = add_tapers_fiber_array(c1)
c6

straight_width3_add_tap_c79a46d8: uid def6f0de, ports ['opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o1', 'opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o2'], references ['bend_euler_1', 'straight_1', 'straight_2', 'bend_euler_2', 'straight_3', 'straight_4', 'grating_coupler_elliptical_trenches_1', 'grating_coupler_elliptical_trenches_2', 'add_tapers_1'], 0 polygons

or

c7 = toolz.pipe(c1, add_tapers, add_fiber_array)
c7

straight_width3_add_tap_c79a46d8: uid def6f0de, ports ['opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o1', 'opt-grating_coupler_ellipti_dd7f7af4-straight_width3-o2'], references ['bend_euler_1', 'straight_1', 'straight_2', 'bend_euler_2', 'straight_3', 'straight_4', 'grating_coupler_elliptical_trenches_1', 'grating_coupler_elliptical_trenches_2', 'add_tapers_1'], 0 polygons

c7.metadata_child['changed']  # You can still access the child metadata

{'width': 3}

c7.metadata['child']['child']['name']

'straight_width3'

c7.metadata['child']['child']['function_name']

'straight'

c7.metadata['changed'].keys()

dict_keys(['component', 'with_loopback'])